Self-tightening clip

ABSTRACT

A self-tightening clip having a planar member and at least one retention member attached to the planar member. The planar member includes an inner perimeter, an outer perimeter, and defines a central axis. The least one retention member including a planar leg portion and a planar hook portion. The leg portion extends from the inner perimeter in a first direction along the central axis. The hook portion projects from the leg portion toward the central axis in a second direction, which is opposite the first direction along the central axis. The hook portion is acute to the central axis and has a free end located on an imaginary perimeter concentric to the inner perimeter of the planar member. The central axis and a plane passing through the hook portion of the at least one retention member form an angle in the range of approximately 20°-30°.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a device that secures a first housingto a second housing. In particular, the present invention relates to aunitary sheet metal clip that self-tightens on a retained housing whenthe retained housing is displaced.

SUMMARY OF THE INVENTION

[0002] The present invention provides a clip having a planar member andat least one retention member attached to the planar member. The planarmember includes an inner perimeter, an outer perimeter, and defines acentral axis. The least one retention member including a planar legportion and a planar hook portion. The arrangement of the leg portionand the hook portion of the retention member create the self-tighteningfeature of the inventive clip.

[0003] The leg portion extends from the inner perimeter in a firstdirection along the central axis. The hook portion projects from the legportion toward the central axis in a second direction, which is oppositethe first direction along the central axis. The hook portion is acute tothe central axis and has a free end located on an imaginary perimeterconcentric to the inner perimeter of the planar member. The central axisand a plane passing through the hook portion of the at least oneretention member form an angle in the range of approximately 20°-30°.Preferably, the angle comprises approximately 24°.

[0004] In a preferred embodiment of the invention, the planar membercomprises an annulus, the imaginary perimeter comprises a circle, andthe at least one retention member comprises a plurality of retentionmembers. Particularly, five retention members uniformly disposed aboutthe inner perimeter of the planar annulus.

[0005] The preferred embodiment further comprises a plurality ofstiffeners. At least one of the plurality of stiffeners is disposed onthe inner perimeter between two of the plurality of retention members.Each of the plurality of stiffeners comprises a lip extending in theengaging direction.

[0006] The present invention also provides a sheet metal clip forsecuring a first generally cylindrical housing member to a secondgenerally cylindrical housing. The clip comprises a planar annulus, aplurality of retention members and a plurality of stiffeners.

[0007] The planar annulus includes an inner perimeter, an outerperimeter, and defines a central axis. The plurality of retentionmembers are uniformly disposed about the inner perimeter of the planarannulus. The plurality of stiffeners are arranged so that at least oneof the plurality of stiffeners is disposed on the inner perimeterbetween two adjacent retention members of the plurality of retentionmembers.

[0008] Each of the plurality of retention members includes a legportion, a hook portion, and an arcuate portion disposed between the legportion and the hook portion. The leg portion extends in an engagingdirection and is substantially parallel to the central axis. The hookportion projects from the leg portion so that the central axis and aplane that passes through the hook portion form an angle in the range ofapproximately 20°-30°. The hook portion has a free end positioned on animaginary circle concentric to the inner perimeter of the planarannulus.

[0009] The present invention also provides a method of retaining a firstgenerally cylindrical housing to a second generally cylindrical housingwhile allowing for relative rotation between the cylindrical housings.The method comprises: (1) providing a sheet metal clip having an annulusand a plurality of retention members, each of the plurality of retentionmembers including a leg portion and a hook portion, the leg portionextending from an inner perimeter of the annulus, the hook portionprojecting from the leg portion toward a central axis of the annulus,the hook portion being acute to the central axis; (2) positioning theannulus of the clip within a retaining portion of the first housingmember; and (3) locating the first housing member proximate the secondhousing member so that a free end of the hook portion of each of theretention members engages a protrusion on the second housing.

[0010] The present invention further provides a method of stamping aclip, which retains a first generally cylindrical housing to a secondgenerally cylindrical housing. The method of stamping comprises: (1)punching a sheet metal circular configuration, the circularconfiguration having an interior cutout so that a plurality ofsubstantially trapezoidal sheet metal members extending toward thecentral axis of the circular configuration; and (2) forming each of theplurality of substantially trapezoidal sheet metal members into aretention members having a planar leg portion and a planar hook portion,the planar leg portion extending from an inner perimeter of an planarannulus created from the circular configuration, the planar hook portionprojecting from the planar leg portion toward the central axis of thecircular configuration, the planar hook portion being acute to thecentral axis.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated herein andconstitute part of this specification, illustrate presently preferredembodiments of the invention, and, together with a general descriptiongiven above and the detailed description of the preferred embodimentsgiven below, serve to explain the principles of the invention.

[0012]FIG. 1 is a partial cross sectional perspective view of the clipof the present invention securing a first housing to a second housing;

[0013]FIG. 2 is a top view of the clip of the present invention;

[0014]FIG. 3 is a cross sectional view of the clip shown in FIG. 2 takenalong the line 3-3 in FIG. 2;

[0015]FIG. 4 is a top view of the sheet metal configuration use to formthe clip of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0016]FIG. 1 shows the sheet metal clip 10 for securing a first housing12 to a second housing 14 of the preferred embodiment. The first housing12 and the second housing 14 are, preferably, generally cylindricalhousing members, however, it is to be understood that otherconfigurations could be employed depending on the particular intendedapplication.

[0017] As shown in FIGS. 1-3, the clip 10 of the present inventioncomprises a planar member 16 and at least one retention member 18attached to the planar member 16. The planar member 16 is held in placeby the first housing 12 so that the retention member 18 can engage aportion of the second housing 14 to secure the housings together.

[0018] The planar member 16 includes an inner perimeter 20, an outerperimeter 22, and defines a central axis 24. The planar member 16 ispreferably a planar annulus with a geometric configuration, such as, forexample, square, rectangle, oval, circle, which is selected tocorrespond to the employed housing configuration. In the preferredembodiment planar member 16 comprises a planar annulus with a circleconfiguration.

[0019] The circular annulus 16 a has an inner circular perimeter 20 aconcentric to an outer circular perimeter 22 a. A planar support surface26 is disposed between the inner and outer perimeters 20, 22.

[0020] The at least one retention member 18 attached to the planarannulus 16, preferably, comprises a plurality of retention members 18uniformly disposed about the inner perimeter 20 of the planar annulus,more particularly, five retention members 18. The clip 10 of thepreferred embodiment further includes a plurality of stiffeners 28attached to the planar member 16 with at least one stiffener between twoof the plurality of retention members 18.

[0021] In the preferred embodiment the planar member 16, the pluralityof retention members 18, and the plurality of stiffeners 28 comprise aunitary sheet of metal. That is, the clip 10 of the present inventionis, preferably, made from sheet metal.

[0022] Each of the plurality of retention members includes a leg portion30, a hook portion 32, and an arcuate portion 34 disposed between theleg portion 30 and hook portion 32. The leg portion 30 and the hookportion 32 are, preferably, also planar and are formed from a bentsubstantially trapezoidal configuration, as discussed below in referenceto FIG. 4.

[0023] The leg portion 30 extends from the inner perimeter 20 of theannulus in a first direction 36 along the central axis 24. The legportion 30 is substantially parallel to the central axis 24. The firstdirection 36 defines an engaging direction. That is, the direction theretention members 18 are moved so that the clip 10 of the presentinvention, which is supported by the first housing, engages the secondhousing 14.

[0024] The hook portion 32 projects from the leg portion 30 toward thecentral axis 24 in a second direction 38. The second direction 38 isgenerally opposite the first direction 36 along the central axis 24. Thehook portion 32 projects from the leg portion 30 so that the centralaxis 24 and a plane (P shown in FIG. 3) passing through the hook portion32 form an angle in the range of approximately 20°-30°. Preferably, theangle comprises approximately 24°.

[0025] The hook portion 32 of each of the plurality of retention membersincludes a free end 40 located on an imaginary perimeter 42 concentricto the inner perimeter 20 of the planar member 16. Because in thepreferred embodiment of the invention the planar member 16 comprises anannulus with a circular inner perimeter 20 a, the imaginary perimeter 42of the preferred embodiment also comprises a circle. The free end 40 ofthe hook portion 32 is positioned to provide face 44. The face 44provides a bearing surface that engages the protrusion 46 of the secondhousing 14 member.

[0026] By providing each of the free ends 40 of each of the hookportions 32 on the imaginary perimeter 42 that corresponds to theselected inner perimeter 20 of the planar member 16, the clip 10 isself-tightening once installed in a housing-retaining position. Moreparticularly, in the preferred embodiment of the invention, the freeends 40 of the respective hook portions 32 of the plurality of theretaining members are uniformly disposed about the imaginary perimeter42. This uniform dispersion of the free ends 40 about the imaginaryperimeter 42 applies a balanced retaining force to the engaged (second)housing that increases as the annulus of the clip 10 is axiallydisplaced in the non-engaging direction or the annulus of the clip 10 ismaintained in a stationary location while the engaged housing is axiallymoved in the engaging direction. The applied force is also believed toincrease because of the unique relationship between the hook portion 32and the leg portion 30 of each of the retention members.

[0027] Even though it is believed that the self-tightening feature ofthe preferred embodiment is best achieved by having a plurality ofretention members uniformly dispersed about the planar annulus, theself-tightening feature of the clip 10 could also be achieved with asingle retention member. A single retention member, however, allows forthe first housing 12 to be removed from the second housing 14 by rockingthe second housing 14 about the central axis 24 so that the singleretention member disengages from the second housing 14. To overcome theremovablilty of the first housing from the second housing 14 when asingle retention member is employed, two retention members disposed atapproximately opposite positions on the inner perimeter 20 could beemployed. In order to ensure that the first housing 12 is secured to thesecond housing 14 so that removal by rocking the first housing 12 isprevented, a clip 10 with three uniformly disposed retention memberscould be employed.

[0028] As shown in FIGS. 1-3, the free end 40 of the hook portion 32 isdisposed at approximately a third of the distance the leg portion 30extends from the planar annulus in the engaging direction. Also, each ofthe leg portions 30 and the hook portions 32 is, preferably,substantially planar members. Because of the dimensioning andconfiguration of the hook portion 32, it is believed that during loadingof the retention member along the central axis 24 opposite the engagingdirection, the hook portion 32 acts as a short column that pushes thehook supporting end of the leg portion 30 away from the central axis 24.While the hook supporting end of the leg portion 30 of the retainingmember is pushed away from the central axis 24, due to the elasticquality of the sheet metal used to form the preferred clip 10, it isbelieved that the loading force is substantially applied to the hookportion 32 of the retaining member until plastic or sheering deformationof the leg portion 30 of the retaining member or the protrusion 46 onthe second housing 14. Instron pull testing of the preferred embodimentof the invention (inner perimeter 20 approximately 21 mm, outerperimeter 22 approximately 27 mm, leg portion 30 approximately 4.25 mm,and hook portion 32 approximately 2.8 mm) has confirmed that theretention ability of the clip 10 of the preferred embodiment continuesto increase until catastrophic failure of the leg portion 30 or thesecond housing 14 occurs at approximately 700 psi.

[0029] The plurality of stiffeners 28 attached to the inner perimeter 20of the planar member 16, annulus, increase the structural rigidity ofthe unitary sheet metal clip 10 of the present invention. At least oneof the plurality of stiffeners 28 is disposed on the inner perimeter 20between two adjacent retention members of the plurality of retentionmembers 18. Preferably, each of the plurality of stiffeners 28 comprisesa lip 28 a extending in the engaging direction from the inner perimeter20 of the planar annulus.

[0030] A cut-out 48 is provided on the inner perimeter 20 of the planarannulus between each of the plurality of retention members and eachstiffener. The cut-out 48 relieves stress created in the support surfaceof the planar annulus. The cut-out 48, preferably, is a semicircleformed in the support surface 26 between the leg of the retention memberand the lip 28 a, which serves as the stiffener.

[0031] The present invention also includes a method of retaining a firstgenerally cylindrical housing to a second generally cylindrical housingwhile allowing for relative rotation between the housings. The method isachieved by providing a sheet metal clip 10 having an annulus and aplurality of retention members. As discussed above, the preferred sheetmetal clip 10 includes five retention members uniformly disposed aboutthe inner perimeter 20 of the annulus, each of the retention membershaving at least a portion of the free end 40 of their respective hookportion 32 located on an imaginary circle that is concentric to theinner perimeter 20 of the annulus.

[0032] After the clip 10 has been provided, the annulus of the clip 10is positioned within a retaining portion of the first housing 12. Then,the first housing 12 is located proximate the second housing 14 so thatthe free end 40 of the hook portion 32 of each of the retention membersengages a protrusion 46 on the second housing 14.

[0033] The present invention also provides a method of stamping a clip10 for retaining a first generally cylindrical housing to a secondgenerally cylindrical housing. The steps of stamping include punchingand forming a single sheet of metal in a uniform sequence of steps.First, a particular configuration is punched from a metal sheet. Thepreferred configuration is a circular configuration having an openinterior so that a plurality of substantially trapezoidal sheet metalmembers 50 extends toward the central axis 24 of the circularconfiguration. Once the particular configuration is punched, each of theplurality of substantially trapezoidal sheet metal members 50 is formedinto a retention members having a planar leg portion 30 and a planarhook portion 32. The planar leg portion 30 is formed to extend from aninner perimeter 20 of a planar member 16, preferably, a circular annulus16 a, created from the particular configuration, while the planar hookportion 32 is formed to project from the planar leg portion 30 towardthe central axis 24 of the particular configuration.

[0034] As shown in FIG. 4, the preferred embodiment of the punchedconfiguration before forming provides the interior as a centrallylocated pentagon 52 with a generally triangular members 54 extendingfrom each corner of the pentagon. After the preferred embodiment ispunched, the geometric configuration is formed so that the planar hookportion 32 is acute to the central axis 24 so that the central axis 24and a plane passing through the hook portion 32 form an angle in therange of approximately 20°-30°, and a stiffener is located on the innerperimeter 20 between each of the plurality of retention members 18.

[0035] While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

I claim:
 1. A self-tightening clip comprising: an planar memberincluding an inner perimeter, an outer perimeter, and defining a centralaxis; and at least one retention member attached to the planar annulus,the at least one retention member including a planar leg portion and aplanar hook portion, the leg portion extending from the inner perimeterin a first direction along the central axis, the hook portion projectingfrom the leg portion toward the central axis in a second direction,opposite the first direction, along the central axis, the hook portionbeing acute to the central axis and having a free end located on animaginary perimeter concentric to the inner perimeter of the planarmember.
 2. The self-tightening clip of claim 1 , wherein the planarmember comprises an annulus and the imaginary perimeter comprise acircle.
 3. The self-tightening clip of claim 2 , wherein the at leastone retention member comprises a plurality of retention members, each ofthe plurality of retention members having a leg portion extending in thefirst direction.
 4. The self-tightening clip of claim 3 , wherein theleg portion of each of the plurality of retention members issubstantially parallel to the central axis.
 5. The self-tightening clipof claim 3 , wherein each of the plurality of retention memberscomprises an arcuate portion disposed between the leg portion and thehook portion.
 6. The self-tightening clip of claim 3 , wherein theplurality of retention members comprises five retention members.
 7. Theself-tightening clip of claim 6 , wherein the five retention members areuniformly disposed about the inner perimeter of the planar annulus. 8.The self-tightening clip of claim 3 , further comprising a plurality ofstiffeners, at least one of the plurality of stiffeners being disposedon the inner perimeter between two of the plurality of retentionmembers.
 9. The self-tightening clip of claim 8 , wherein each of theplurality of stiffeners comprises a lip extending in the engagingdirection.
 10. The self-tightening clip of claim 8 , wherein theannulus, the plurality of retention members, and the plurality ofstiffeners comprise a unitary sheet of metal.
 11. The self-tighteningclip of claim 1 , wherein the central axis and a plane passing throughthe hook portion of the at least one retention member form an angle inthe range of approximately 20°-30°.
 12. The self-tightening clip ofclaim 11 , wherein the angle comprises approximately 24°.
 13. A sheetmetal clip for securing a first generally cylindrical housing member toa second generally cylindrical housing, the clip comprising: a planarannulus including an inner perimeter, an outer perimeter, and defining acentral axis; a plurality of retention members uniformly disposed aboutthe inner perimeter of the planar annulus, each of the plurality ofretention members including a leg portion, a hook portion, and anarcuate portion disposed between the leg portion and hook portion, theleg portion extending in an engaging direction and being substantiallyparallel to the central axis, the hook portion projecting from the legportion so that the central axis and a plane passing through the hookportion form an angle in the range of approximately 20°-30°, the hookportion having a free end positioned on an imaginary circle concentricto the inner perimeter of the planar annulus; and a plurality ofstiffeners, at least one of the plurality of stiffeners being disposedon the inner perimeter between two adjacent retention members of theplurality of retention members.
 14. The clip of claim 13 , wherein eachof the plurality of stiffeners comprises a lip extending in the engagingdirection.
 15. The clip of claim 13 , wherein each of the plurality ofretention members comprise a bent substantially trapezoidalconfiguration.
 16. The clip of claim 13 , further comprising a cut-outon the inner perimeter of the planar annulus between each of theplurality of retention members and each stiffener.
 17. The clip of claim16 , wherein the cut-out comprises a semicircle.
 18. The clip of claim13 , wherein the plurality of retention members comprises five retentionmembers uniformly disposed on the inner perimeter.
 19. The clip of claim13 , wherein the angle comprises approximately 24°.
 20. A method ofretaining a first generally cylindrical housing to a second generallycylindrical housing while allowing for relative rotation between thehousings, comprising: providing a sheet metal clip having an annulus anda plurality of retention members, each of the plurality of retentionmembers including a leg portion and a hook portion, the leg portionextending from an inner perimeter of the annulus, the hook portionprojecting from the leg portion toward a central axis of the annulus,the hook portion being acute to the central axis; positioning theannulus of the clip within a retaining portion of the first housingmember; and locating the first housing member proximate the secondhousing member so that a free end of the hook portion of each of theretention members engages a protrusion on the second housing.
 21. Themethod of claim 20 , the step of providing further comprises: providingthe sheet metal clip with five retention members uniformly disposedabout the inner perimeter of the annulus, each of the retention membershaving at least a portion of the free end of their respective hookportions located on an imaginary circle that is concentric to the innerperimeter of the annulus.
 22. A method of stamping a clip for retaininga first generally cylindrical housing to a second generally cylindricalhousing, comprising: punching a particular sheet of metal configuration,the configuration having an interior cutout so that a plurality ofsubstantially trapezoidal sheet metal members extending toward thecentral axis of the configuration; and forming each of the plurality ofsubstantially trapezoidal sheet metal members into a retention membershaving a planar leg portion and a planar hook portion, the planar legportion extending from an inner perimeter of a planar annulus createdfrom the circular configuration, the planar hook portion projecting fromthe planar leg portion toward the central axis of the circularconfiguration, the planar hook portion being acute to the central axis.23. The method of claim 22 , wherein the step of punching furthercomprises punching circular configuration; and the step of formingfurther comprises forming each retention members to have the planar legportion extending from an inner perimeter of a planar annulus createdfrom the circular configuration.
 24. The method of claim 23 , whereinthe step of punching further comprises providing the interior cutout asa centrally located pentagon with a generally triangular membersextending from each corner of the pentagon.
 25. The method of forming aclip of claim 24 , wherein the step of forming further compriseslocating the planar hook portion acute to the central axis so that thecentral axis and a plane passing through the planar hook portion form anangle in the range of approximately 20°-30°.
 26. The method of claim 22, further comprising forming a stiffener on the inner perimeter betweeneach of the plurality of retention members.